Information will be sought on the mechanism that Sendai virus, a mammalian paramyxovirus, used to synthesize viral proteins. The number and size of virus-specific proteins in cells infected with Sendai virus will be determined by polyacrylamide gel electrophoresis. Pulse-chase experiments will be performed to decide whether paramyxovirus proteins are synthesized as individual proteins or as polycistronic polypeptides which are subsequently cleaved. Paramyxovirus protein synthesis is presumably directed by complementary RNAs-single-stranded RNA molecules smaller than viral genomes and complementary in base sequence to viral genomes. Complementary RNAs will be examined for the heterogeneity which would be expected of viral messenger RNA. Polyacrylamide gel electrophoresis, density gradient centrifugation, and column chromatography will be employed to fractionate complementary RNAs. If substantial fractionation is achieved the complementary RNAs will be examined for evidence of transcriptional control. The role of the virion RNA polymerase in virus replication will be explored in experiments to determine if the products of the virion enzyme direct the synthesis of viral protein, and if so, to determine if any unique early proteins are synthesized. The product of the virion transcriptase will be compared with the product of the transcriptase which functions in infected cells late in infection.